Titanium dioxide pigmented paints extended with synthetic sodium alumino silicate pigment



United States Patent 3,509,082 TITANIUM DIOXIDE PIGMENTED PAINTS EX-TENDED WITH SYNTHETIC SODIUM ALU- MINO SILICATE PIGMENT Robert K. Mays,Havre de Grace, Md., assignor to J. M. Huber Corporation, Locust, N.J.,a corporation of New Jersey No Drawing. Continuation of application Ser.No.

359,457, Apr. 13, 1964, which is a continuation-inpart of applicationSer. No. 113,600, May 31, 1961. This application Oct. 7, 1968, Ser. No.784,974

Int. Cl. C08f 45/04 US. Cl. 260-22 3 Claims ABSTRACT OF THE DISCLOSURETitanium dioxide pigmented aint compositions are extended by replacingfrom 10% to 40% by weight of the titanium dioxide from a finely dividedsynthetic, amorphous sodium alumino silicate pigment.

This application is a continuation-in-part of US. application Ser. No.113,600, filed May 31, 1961, entitled Paint, and now abandoned.

This invention relates to paint compositions containing pigmentscomposed of a mixture of titanium dioxide and finely divided, synthetic,amorphous, sodium alumino silicates of submicron particle size.

More particularly this invention relates to latex emulsion paints andalkyd flat paints containing a pigment composed of a mixture of titaniumdioxide and finely divided, synthetic, amorphous, sodium aluminosilicates of submicron particle size.

Both latex or water-emulsion paints and alkyd flat paints for bothinterior and exterior applications are widely used. The latex emulsionpaints are used because they are safe, odorless, very fast drying, easyto apply and, when spilled, are easily removed from clothes, brushes andfloors by washing with water.

The alkyd flat paints are used because they have good appearance, hidingpower, and levelling.

The paint latices used in the water-emuslion paint formulations arecopolymers which are produced from two or more unsaturated polymerizablecomponents in the presence of surface active agents acting asstabilizers, and one or more per compounds acting as polym rizationaccelerators, to form an aqueous emulsion polymer system. Theunsaturated compounds used, for example, are styrene, butadiene, vinylacetate, acrylates such as methyl methacrylate, ethyl acrylate, andacrylonitrile, vinyl chloride, vinyl butyrate, vinyl toluene, isopreneand the like. Among useful paint latices are copolymers and terpolymerscomprising monovinyl aromatic hydrocarbons containing a single reactivecenter of polymerization, and aliphatic conjugated diolefins. As aclass, the water emulsion or latex paints are well known to the art.Included in the preferred types of water emulsion paints useful in thepresent invention are styrene-butadiene, polyvinyl acetate (PVAc), andacrylic resin paints. Representative acrylic resin emulsions aredisclosed in Rhoplex AC-33 for Exterior Paints, 6th annual progressreport by Rohm and Haas Company (October 1959).

Alkyd resins are the complexes resulting from the reaction of polyhydricalcohols and resinifying carboxylic orgariic acids such as polybasicacids and their anhydrides.

Today two major groups of alkyd resins are widely used in paints andvarnishes, the phthalic alkyd resins, and the maleic alkyd resins. Theformer comprises all alkyd resins made with phthalic acid or anhydrideas the major polybasic acid reactant. It includes those modifications inwhich maleic acid or another polybasic acid constituent has beensubstituted in minor proportions for phthalic acid.

The latter group comprises resins based on maleic anhydride or acidsderived from maleic anhydride by the Diels-Alder or other additionreactions. All the primary polybasic acids used in preparing theseresins contain an unsaturated hydrocarbon group. This class includesresins manufactured from fumaric acid, the trans isomer of maleic acid.

Although the basic reactions involved in the preparation of alkyd resinsare simple, the chemistry of the whole is complex when all theramifications are considered.

All the resins of the phthalic type are modifications of glycerolphthalate. Other polyhydric alcohols such as ethylene, diethylene, andtriethylene glycols, sorbitol, mannitol, and pentaerythrito-l are alsoused.

Agents known as modifying agents are used to partially esterify thepolyhydric alcohol before reaction with the phthalic or maleic acid oranhydride. The type and degree of modification plays a susbtantial partin the final properties of the resin.

Phthalic alkyd resins are made with modifiers such as maleic anhydride,fumaric acid, succinic acid, adipic acid, sebacic acid, citric acid,malic acid, tartaric acid, diph nic acid and 1,8 naphthalic acid. Theleading modifiers particularly useful in coating compositions and paintsare fatty acids and their glycerol esters as well as the wellknowndrying oils and their fatty acids. Examples are soybean, linseed,perilla, sunflower, fish, oiticica, tung, tall, and dehydrated castoroils. Non-drying oils such as cottonseed, castor, and coconut oils arealso used.

Some derivatives of the foregoing are also used.

Alkyd paints are divided into three types, i.e., longoil alkyds whichcontain from 64 to of oil to 28 to 23% phthalic anhydride, medium-oilalkyds which contain from 53 to 61% oil to 36 to 30% phthalic anhydride,short-oil alkyds having 42 to 50% oil to 45 to 39% phthalic anhydride.The oil length determines such important properties as rate of drying,solubility, compatibility, and durability.

The mediumand long-oil alkyds are most widely used in brushingformulations of the air-drying types. The shortoil resins are the bakedry types.

The maleic alkyd resins are also useful in paints with propertiessimilar to the comparable phthalic resins.

In formulating both the water-emulsion paints and the alkyd resin flatpaints its is necessary to incorporate a pigment which will impart tothe paint desirable optical properties such as hiding power or opacity,brightness, and reflectance. The pigment additives affect otherproperties of the paint and this must be taken into consideration whenselecting a pigment. The properties of paints affected by pigmentadditives are viscosity, viscosity stability, washability, scuffresistance, scrub resistance, stain removal, adhesion, flex, gloss,settling, freeze-thaw stability and enamel holdout.

The pigment in use today which is most suitable for beneficiallyaffecting the above desirable properties in alkyd flat paints andwater-emulsion paints is titanium dioxide. This pigment, however, is arelatively expensive paint pigment and it is difiicult to prevent itfrom reagglomerating after grinding. The paint industry, therefore, hasbeen faced with the problem of finding an inexpensive pigment for use inwater-emulsion and alkyd flat paints which will either totally orpartially replace titanium dioxide aud not adversely affect theproperties of the paint. The extenders in use today such as the calcinedclays, calcium carbonate, magnesium silicate, diatomaceous silicas andtheir reaction products, e.g., synthetic calcium silicates, are notcompletely satisfactory since they tend to reduce the optical propertiesof the titanium dioxide.

I have discovered a relatively inexpensive pigment useful as a titaniumdioxide extender in both water-emulsion paints and alkyd resin flatpaints which not only maintains the optical properties of the paintscontaining the extended pigments, but also improves them withoutadversely alfecting the other paint properties previously listed.Chemically, the pigment is a finely divided sodium alumino silicate ofsubmicron particle size and has a pH of 6.5 to 10.5. Pigments of thistype are disclosed in U.S. Patents 2,739,073 and 2,848,346 and asdisclosed in these patents, the sodium alumino silicate pigments have0.8 to 1.3 moles of Na per mole of A1 0 and at least 4 moles of Si0 permole of Na O.

It is an object of this invention to provide water-emulsion paints andalkyd resin fiat paints of superior optical properties containingtitanium dioxide extended with relatively inexpensive sodium aluminosilicate pigments.

A further object of this invention is to provide wateremulsion paintsand alkyd resin flat paints containing titanium dioxide extended withsodium alumino silicate pigments which exhibit optical propertiessuperior to those paints containing unextended titanium dioxide.

A still further object of this invention is to provide water-emulsionpaints and alkyd resin flat paints containing highly dispersed pigmentscomprising titanium doxide, and finely divided sodium alumino silicate.

Another object of this invention is to provide wateremulsion paints ofimproved viscosity stability containing titaanium dioxide extended withsodium alumino silicate pigments.

Another further object of ths invention is to provide alkyd resin fiatpaints of improved flatness properties containing titanium dioxideextended with sodium alumino silicate pigments.

A still further object of this invention is to provide alkyd resin flatpaints of accelerated drying time containing titanium dioxide extendedwith sodium alumino silicate pigments.

Other advantages and objects will be apparent from the followingspecification.

The utilization of sodium alumino silicate pigments to extend thetitanium dioxide pigment in both water-emulsion paints and alkyd resinflat paints results in a paint with optical properties, particularlyhiding power, superior to those obtained when other extender pigmentsare used. The hiding power, as measured by the contrast ratio of thepaints containing titanium dioxide extended with sodium alumino silicatepigments, is superior to that obtained in paints containing otherextenders used with titanium dioxide. Furthermore, when sodium aluminosilicate pigments are used to extend titanium dioxide pigments inpaints, a synergism is effected on the hiding power or opacity of thetitanium dioxide when up to 40% of the weight of the titanium dioxide isreplaced by sodium alumino silicate on either an equal weight or avolume basis.

Table I illustrates the superiority of sodium alumino silicate pigmentsover the conventional titanium dioxide extender, diatomaceous silica, ina PVAc emulsion paint.

TABLE I.-POLYVINYL ACETATE EMULSION PAINT [Ball mill grind] Sodiumalumino silicate Control extended Formula:

Titanium (rutile), parts by weight 175 175 Diatornaceous silica, partsby weight. 50 Sodium alumino silicate, parts by weight 50 Kaolin clay,parts by weight 200 200 Whiting, parts by weight 100 100 PVAc emulsion(55%), parts by weight 175 175 Total pounds/100 gallons 1,190 1, 199Pigment volume concentration, percent-.." 65 65 Test data:

86. 45 91. 0 90. 40 92. 1 0. 957 0. 988 11. 11. 88 Viscosity,

1 month 84 78 2 months 84 78 3 months 84 78 Freeze-thaw stability, 5 cycles. OK OK Gloss, percent 60 specu1ar 12 12 Dryset, minutes 90 90Washability. Equal Scufi rcsistan Equal Scrubability. Equal FlexingEqual Enamel holdout .l Equal Settling Equal The data in Table Iindicate that when diatomaceous silicate is used as an extender fortitanium dioxide the paint exhibits a contrast ratio of 0.957. Whensodium alumino silicate replaces all the conventional extender, thecontrast ratio increases to 0.988. As discussed in Gardner et al.,Physical and Chemical Examination of Paints, Varnishes, Lacquers andColors, Eleventh Edition, 1950, Chapter 1, the closer to 1.0 thecontrast ratio is, the greater the hiding power of the paint. Hidingpower is a measure of the opacity of a paint and its capacity toobliterate the substrate upon which it is spread. As stated by Gardneret al., page 10, complete hiding is reached when the contrast ratio is0.98. From the data in Table I, it is thus apparent that, when sodiumalumino silicate is used as an extender of titanium dioxide in PVAcWateremulsion paints, substantially complete hiding power is attainedwhere a conventional titanium dioxide extender is deficient in thisrespect.

Table I also indicates that sodium alumino silicate, when used as anextender for titanium dioxide in place of a conventional extender inPVAc water-emulsion paints, does not sacrifice the other importantproperties of the paint at-the expense of superior hiding power.

The following tables illustrate the effects of sodium alumino silicatepigments used as an extender for titanium dioxide in variouswater-emulsion and alkyd resin flat paint formulations.

TABLE II.-IOLYVINYL ACETATE EMULSION PAINT [B all mill grind] ControlSodium alumino silicate Percent TiO replacement, weight basis 0 10 20 3040 Formula:

Titanium (rutile)- 175 157. 5 140 122. 5 105 Sodium alumino silicate" 0l7. 5 35 52. 5 70 Diat-omaceous silica 50 50 50 5O 50 Kaolin clay 0OWhiting PVAc emulsion (55%) Total pounds/gallon.

Density, pounds/gallon PVC, percent Cost savings/ gallons,

percent 0 4.96 9 92 14. 8B 19. 84

Optical data:

Black reflectance, percent"..- 86. 4 87.9 86. 7 86. 0 83.6

White reflectance, percent... 90. 4 91. 8 90.6 90. 0 89.2

Contrast ratio 0. 957 0. 958 0. 958 0. 956 0. 938

Sodium alumino silicate Percent TiO replacement,

weight basis 10 20 30 40 Formula:

Titanium (rutile) 165 148. 132 115. 5 99 Sodium alumino silicate. 0 16.5 33 49. 5 66 47 47 7 47 47 188 188 188 188 188 94 94 94 94 94 194 197197 197 197 1, 163 Density, pounds/gallon 11.62 11. 57 11. 52 11. 4711.42 PVC, percent r 62 Cost savings/100 gallons,

percent 0 5. 09 10. 17 15. 26 20. 34 Optical data:

Black reflectance, percent. 78 79. 55 80. 90 81. 60 80. 6 Whitereflectance, percent 87.8 88. 30 88. 90 89. 30 80. 20 Contrast ratio0.888 0.900 0. 911 0. 914 0. 903

TABLE I\'.ACRYLIC EMULSION PAINT Control Sodium alumino silicate PercentTiO replacement,

Rhoplex AC-33, an emulsion of a 100% acrylic ester polymer ior waterbased paints manufactured by Rohmand Haas Company of Phlladelphia,Pennsylvania, the exact composition of which is unknown.

of the invention in respect to contrast ratio. The synergistic effect ofsodium alumino silicate on the optical properties of the water-emulsionpaints containing titanium dioxide is apparent from the fact that, whenup to 40% of the titanium dioxide is replaced, either on a volume basisor a weight basis the contrast ratio of the paint increases and isgreater than at 0% replacement. Generally, at greater than 40%replacement in both alkyd resin flat paints and water-emulsion paints,the optical properties of the paint are diminished to less than at 0%replacement. The optical improvements using sodium alumino silicatepigments are achieved without any adverse effect on other paintproperties and with a decrease in the raw material cost of the paint.With the synthetic pigment used in this invention, the properties ofviscosity and viscosity stability, washability, scuff resistance,scrubability, adhesion, flexing, gloss, settling, freeze-thaw stability,and enamel holdout are equal to or better than control paints withoutthe addition of the synethic, amorphous, sodium alumino silicatepigments used in this invention. Since these extender pigments costabout half that of titanium dioxide, substantial savings over presentformulation raw materials costs can be obtained by using sodium aluminosilicate pigments without sacrifice of paint properties.

The following table illustrates the maintenance of optical and otherproperties of alkyd resin fiat paints with various volume replacementsof titanium doxide by sodium alumino silicate.

TABLE V.ALKYD RESIN FLAT PAINT [Pounds/100 gallons] Control Sodiumalumino silicate Percent TiOQ replacement, (volume basis) 0 Formula:

Wallkyd 0-1956-35 (35% NV) (phthalic anliydride mixed vegetable oil puredrying a1kyd)..

TiO

24% lead naphthenate drier 6% cobalt naphthenate drier Anti-skinningagent (Exkin #2 it me antioxidan Total pounds/100 gallons Raw materialsavings per gallon Opticla data: Contrast ratio (3 mil drawdow n) Dryingcharacteristics:

Set to touch (minutes) Tack free (minutes)...

Full hardness Overuight.

The data indicate that when as little as 5% titanium dioxide is replacedin alkyd flats and as little as 10% is replaced in water-emusion paintsby sodium alumino silicate, the hiding power of the paint is notsacrificed and in some cases increases with a significant decrease inthe cost of the raw materials. This is a result of the betterutilization of the titanium dioxide, caused by the smaller sodiumalumino silicate particles. The sodium alumino silicate effects a moreefiicient dispersion of the titanium dioxide pigments, thereby enhancingthe optical qualities of the prime pigment. The contrast ratio in TableV diminishes somewhat but this loss is much smaller than would beexpected from the reduction in the amount of titanium dioxide and itsreplacement with sodium alumino silicate which imparts very littlehiding power to paints. Experiments have shown that when 100% TiO isreplaced in alkyd flat paints by sodium alumino silicate the contrastratio is 0.19. Table V also illustrating the quick drying qualitiesimparted to the alkyd flats by the use of sodium alumino silicate.

The sodium alumino silicate pigments in combination with titaniumdioxide in paints produce optical effects greater than is indicated froma purely additive basis. Tables II, III, IV and V adequately illustratethis feature wron s TABLE VI.ALKYD FLAT PAINTS PERFO RMANCE DATA ControlSodium alumino silicate Percent TiO2 replacement,

The data in this table indicate that at up to 40% replacement, verylitle, if any, deterioration of the paint properties occurs.

The viscosity of alkyd resin flat paints and water-emulsion paints has atendency to increase with time. The effect is more noticeable in thelatter and is undesirable because too great an increase in viscosityresults in a paint which is unusable without further reduction. However,when the sodium alumino silicate pigments useful in this invention areused to replace up to 40% of titanium dioxide, in general the viscositystability of the water-emulsion paints is improved and the viscositystability of the alkyd resin fiat paints is maintained.

TABLE TIL-VISCOSITY CHANGE IN PAINTS [All in Krebs units] Poly-Butavinyl diene- Alkyd acetate, styrene, Acrylic, resin, Qmonths 7monthstimcnths 8 days Parts TiO replaced by sodium alumino silicate:

NOTE.-+ means viscosity increase; means viscosity decrease.

TABLE VIIL-EFFECT OF SODIUM ALUMINO SILICATE PIGMENTS ON THE GLOSS OF ANALKYD RESIN PAINT Control Sodoium alumino silicate Percent Tl02replacement,

. volume basis 0 5 20 30 40 60 specular gloss, percent 85 60 40 20 13 9The data in Table VIII indicate that replacement of up to 40% titaniumdioxide results in a significant increase in fiatting of the alkyd resinpaint. At more than 40% replacement, the gloss is decreased even more,however, other paint properties are adversely affected at greater than40% replacement of titanium dioxide.

While I do not intend to be bound by a specific theory, the reasons forthe improved optical properties of the paints are that the sodiumalumino silicate causes an improved dispersion of the titanium dioxide.The effective aggregate size of the synthetic, amorphous, sodium aluminosilicate is 0.2 micron. The titanium dioxide used herein has anaggregate size of 2.0 microns, which is its known most efficientaggregate size in paints. The very large number of relatively smallextender pigment aggregates separate the larger titanium dioxideaggregates, thus achieving more efiicient dispersion; since the extenderappears to coat or condition the titanium dioxide, the tendency of thetitanium dioxide to reagglomerate into larger less effective aggregatesafter removal of dispersion energy is reduced. This results in a betterutilization of the high refractive index of titanium dioxide and a moreeffective use of its optical properties.

The phrase sodium alumino silicate pigment as used herein means asynthetic, finely divided, amorphous material with a mean particlediameter of 0.02 micron and a pH in the range from 6.5 to 10.5. Suchmaterials are described in detail in US. Patents 2,739,073 and2,848,346. These pigments are distinguished from naturally occurring andsynthetic zeolites as well as naturally occurring and syntheticmolecular sieves.

While the properties of the sodium alumino silicate in both alkyd resinfiat paints and latex Water-emulsion paints have been given in only afew formulations, it is intended that these examples be representativeof the classes of paints described and useful in interior, exterior, andinterior-exterior applications which utilize titanium dioxide as apigment. The sodium alumino silicate incorporates easily inwater-emulsion paints and alkyd resin flat paints and is handled likeany other wettable pigment.

The term volume replacement is used to mean the replacement of titaniumdioxide by a volume equal to that removed from the formulation. Forexample, a 40% replacement on a volume basis means that 40% by weight orvolume of the titanium dioxide has been replaced in the formula by anequal volume of extender pigment.

The term weight replacement is used to indicate that the weight oftitanium dioxide removed from the formulation is replaced by an equalWeight of extender pigment.

The foregoing is illustrative only and additional modifications may bemade without departing from the substance of the invention as defined inthe appended claims.

What is claimed is:

1. The method of extending titanium dioxide pigments in water emulsionpaints selected from the group consisting of polyvinyl acetateemulsions, styrene-butadiene Iatexes and emulsions of acrylic esterpolymers to produce a dispersion of tiatnium dioxide having greaterhiding power as measured by the optical contrast ratio than the paintwithout said extension of the titanium dioxide by replacing from 10% upto 40% by weight of the titanium dioxide pigment in the paintformulation by a finely divided synthetic, amorphous sodium aluminosilicate pigment having an effective aggregate size of 0.2 microns, amean particle diameter of 0.02 micron and a pH in the range of from 6.5to 10.5 with 0.8 to 1.3 moles of Na O per mole of A1 0 and at least 4moles of SiO per mole of Na O.

2. The method of claim 1 wherein the dispersion has a hiding power asmeasured by the optical contrast ratio of at least 0938/0957 of theoptical contrast ratio of the paint Without said extension of thetitanium dioxide.

3. The method of extending titanium dioxide pigments in alkyd resin flatpaints to product a dispersion of titanium dioxide having a hiding poweras measured by the optical contrast ratio of at least (197/098 of theoptical contrast ratio of the paint without said extension of thetitanium dioxide by replacing from 5% up to 40% by volume of thetitanium dioxide pigment in the paint for- 'rnulation by a finelydivided synthetic, amorphous sodium alumino silicate pigment having aneffective aggregate size of 0.2 micron, a mean particle diameter of 0.02micron and a pH in the range from 6.5 to 10.5 with 0.8 to 1.3 moles ofNa O per mole of A1 0 and at least 4moles of SiO per mole of N320.

References Cited UNITED STATES PATENTS 2,848,346 8/ 1958 Berforell106-288 2,877,130 3/1959 Caron et al. 3,037,881 6/ 1962 McDowell.

MURRAY TILLMAN, Primary Examiner W. J. BRIGGS, SR., Assistant ExaminerUS. Cl. X.R.

